|Publication number||US6874913 B2|
|Application number||US 10/151,219|
|Publication date||Apr 5, 2005|
|Filing date||May 17, 2002|
|Priority date||Dec 2, 1999|
|Also published as||CA2393260A1, EP1238227A1, US6854855, US20010040799, US20020172032, WO2001044716A1, WO2001044716A9|
|Publication number||10151219, 151219, US 6874913 B2, US 6874913B2, US-B2-6874913, US6874913 B2, US6874913B2|
|Inventors||James F. Munro, John A. Futhey|
|Original Assignee||Reflexite Corporation|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (13), Non-Patent Citations (1), Referenced by (10), Classifications (8), Legal Events (8)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application is a divisional of U.S. application Ser. No. 09/726,239, filed on Nov. 29, 2000, which claims the benefit of U.S. application Ser. No. 60/208,339, filed May 31, 2000, and U.S. application Ser. No. 60/168,586, filed on Dec. 2, 1999, the entire teachings of the above applications are incorporated herein by reference.
Luminaires typically include a lighting source, a waveguide, and microprisms used to redirect the light in a desired direction. These luminaires are used to provide a more uniform light distribution than conventional light systems and alleviate glare in applications such as office space, boardrooms, and customer service centers.
A luminaire is provided which includes a light source, a light guide that receives light radiating from the light source, and a tilted prism array for redirecting the light in a first direction. In one embodiment, the prism array, which can include linear prisms, includes a cross-sectional profile that periodically alternates orientation along the light guide. The linear prisms can have included angles of 25, 90, and 65 degrees. The prism array can alternate or flip-flop in orientation every few millimeters, for example, one to two millimeters. A tilted prism can have two sides which meet at a peak with a first length from the valley to the peak on one side and a second length from the valley to the peak on a second side of the prism, where the first length is different in length from the second length, thereby tilting or canting the prisms. The tilting angle of the prisms is between the optical axis and a line perpendicular to the window side. The tilting angle can be in the range between about 20 and 70 degrees.
The prism array can include peaks and valleys that form the cross-sectional profile that alternates along a first axis. The prism array can also include a second cross-sectional profile that alternates orientation along a second axis that is different than the first axis, such as substantially perpendicular or offset about 60 degrees relative to the first axis. The prism array can further include a third cross-sectional profile that alternates orientation along a third axis that is different than the second axis and the first axis. In one embodiment, the third axis is offset about 60 degrees relative to the second axis. The prism array can be disposed on a top surface of the light guide.
An optical microstructure is also provided which includes a tilted prism array that periodically alternates orientation of the tilted prism array along a first axis. The prism array can also include a cross-sectional profile that includes peaks and valleys that periodically alternate orientation along a second axis. In alternative embodiments, the prism array includes another cross-sectional profile that periodically alternates along a third axis. The optical microstructure can be disposed on a first surface of a film. A prism array can be disposed on a second surface of the film. The prism array on the second surface can be tilted and periodically alternate orientation along at least one axis. The purpose of the periodic alternate orientation of the prism angles is to create alternating bands of bright and dark lines which can be seen viewing the surface of the luminaire. Very small or fine pitch prisms that are not visible to the human eye beyond 0.5 meters can be made to look like macro prisms because of the visibility of the bright and dark bands. Low cost manufacturing concepts, such as continuous casting, can be used to form the precision fine pitch alternating prism groups and achieve the appearance of a precision macro prism, for example, 0.508 to 2.54 mm (0.02 to 0.1 inch) pitch, which would normally be made with a more expensive manufacturing concept, such as compression molding.
Multi-faceted prisms can be used, for example, prisms that have more than one slope on a facet. Further, prisms can be used which have curved facets or curved prism tips and valleys. These features are used to smooth the resulting light distribution.
A method for redirecting light is also provided which includes providing a light source, receiving light radiating from the light source in a light guide, and redirecting the light in a first direction with a tilted prism array that includes a cross-sectional view that periodically alternates orientation along a first axis. The tilted prism array can include a second cross-sectional profile that periodically alternates orientation along a second axis that is different than the first axis. The tilted prism array can further include a third cross-sectional profile that includes peaks and valleys that periodically alternate orientation along a third axis which that is different than the second axis.
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.
A description of preferred embodiments of the invention follows. Generally, the invention is directed to a backlit display apparatus (“BLDA”) having a coarse appearance. An example of a BLDA is disclosed in U.S. Pat. No. 5,629,784, issued to Abileah et al. on May 13, 1997, the teachings of which are incorporated herein in its entirety by reference.
When viewed from below, one set of fine pitch prisms 12 is generally oriented to reflect light towards the viewer, and the neighboring pair away from the viewer. Thus, the viewer sees a set of alternating bright and dark lines, which can be referred to as a coarse appearance. It is understood that the number of prisms 12 within a prism grouping is variable, which means that the width of a group and its coarseness can be easily controlled.
Further, the output light distribution is such that the image of the light source 14, such as a cylindrical bulb, is masked. It is noted that the prisms 12 of
The table below compares the viewing angle, the measured luminance for the luminaire 19 of FIG. 8 and theoretical output for a luminaire having a baffle such as the luminaire 22 of FIG. 9. In this embodiment, the pitch of the prisms is about 0.254 mm (0.01 inches).
Theoretical with Baffle
The linear prisms 12 as described above can be referred to as a one-dimensional structure. That is, the prism structures 12 have peaks and valleys that form a cross-sectional view running along one axis. In alternative embodiments, the prisms 12 can include multiple-dimensional structures, such as two-dimensional structures and three-dimensional structures that form cross-sectional profiles along second and third axes, respectively.
For example, in the embodiment of
A luminaire having cross-sectional profiles formed at 60 degrees relative to one another is shown in
In alternative embodiments, optical microstructures can be formed on, laminated to, or otherwise provided on sheets, panels, or films for use in luminaires in which control of light distribution is desired. Furthermore, each side of the sheet, panel, or film can have an optical microstructure thereon. These optical microstructures can have tilted prism arrays which alternate orientation along one or more axes.
In any of the disclosed embodiments, multi-faceted prisms can be used, for example, prisms that have more than one slope on a facet. Further, prisms can be used which have curved facets or curved prism tips and valleys. These features can be used to smooth the resulting light distribution.
While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.
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|WO2014067009A2 *||Oct 31, 2013||May 8, 2014||Fluxwerx Illumination Inc.||Light extraction elements|
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|U.S. Classification||362/330, 362/332, 362/339|
|Cooperative Classification||G02B6/0058, G02B6/0038|
|European Classification||G02B6/00L6O16, G02B6/00L6O4G|
|Aug 19, 2008||FPAY||Fee payment|
Year of fee payment: 4
|Jan 12, 2009||AS||Assignment|
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Free format text: PATENT COLLATERAL ASSIGNMENT AND SECURITY AGREEMENT;ASSIGNOR:REFLEXITE CORPORATION;REEL/FRAME:027354/0839
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|Apr 5, 2013||LAPS||Lapse for failure to pay maintenance fees|
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Effective date: 20130405